Nuchal Translucency Calculator

Nuchal Translucency Calculator

The nuchal translucency calculator can help determine your pregnancy’s gestational age and the likelihood of genetic abnormalities.

The definition of nuchal translucency, calculation methods, disorders associated with it, and many more will be covered in this article.

What is the Nuchal translucency calculator?

The Nuchal translucency calculator determines the percentile of the nuchal fold thickness, and it is compared to the nuchal translucency measuring table. This technique estimates the probability of genetic abnormalities during a specific pregnancy.

To calculate the chance of Down syndrome, the Calculator uses a model that considers the combination of the crown-rump length, maternal age, and NT thickness. Due to the lack of serum analytes, this combination is sometimes known as “NT alone.” A Calculator is a screening tool; it does not offer diagnostic data.

The combined test (nuchal translucency measurement and biochemical indicators) is more effective for first-trimester screening than the measurement of nuchal translucency alone.

When estimating risk in singletons, using NT alone is less effective than combining NT and serum screening tests. High-order multiple pregnancies may benefit from using NT the most (i.e., 3 or more fetuses). The calculation’s findings shouldn’t be used in place of clinical judgment.

What is Nuchal translucency?

Nuchal translucency is the fluid seen under the neck of unborn children. It can be spotted via ultrasound from 11 weeks and 2 days until 14 weeks and 1 day into the pregnancy.

It has been shown that babies with anomalies accumulate more NT fluid throughout the first trimester at the back of their necks. After the second trimester, NT cannot be observed. So, it’s better to use the Nuchal translucency calculator.

What is the Nuchal translucency test?

The nuchal translucency test is used to measure the nuchal fold thickness. This is a tissue region near the back of a developing baby’s neck.

This thickness measurement aids your doctor in determining the likelihood that your child will have a chromosomal abnormality like Down syndrome and other genetic issues. The nuchal translucency calculator is one of the important tools that is needed by the doctor in determining genetic abnormalities.

What to expect during a Nuchal translucency scan?

This fold’s thicker layer is associated with greater fetal death, genetic diseases, and other severe anomalies.

The health of a fetus cannot be 100% assured by a normal NT scan; other significant criteria, such as the mother’s age, blood tests, and the presence of a nasal bone, must be taken into account for a better degree of result certainty.

Your medical professional will:

  • Calculate the nuchal translucency (NT) and compare it to the normal range.
  • Determine a fetus’s gestational age and crown-rump length.
  • Verify other crucial body parts of the fetuses, such as the nasal bone’s presence or absence.
  • Assess and take note of the mother’s age.
  • In blood tests, assess the levels of human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein-A (PAPP-A).

How is the Nuchal translucency test performed?

With the nuchal translucency scan, you can get an abdominal or vaginal ultrasound in the early stages of pregnancy. Your body shape and how far you are in your pregnancy will both be taken into account by your sonographer when deciding which technique to use.

If your scan is transabdominal performed, you will be requested to drink a few cups of water in advance, so your bladder is full. This facilitates visual inspection of your uterus (womb). The sonographer will apply gel and delicately slide the ultrasound probe across your abdomen.

A tiny, lubricated ultrasound probe is delicately put into your vagina if your scan is transvaginally performed. Because the probe is closer to your uterus during a scan done this way, more precise images can be obtained. Ultrasounds do not endanger your unborn child or raise your chance of miscarriage.

The mother also undergoes a blood test. When these two tests are combined, they can determine whether the infant may have Down syndrome or another genetic condition.

Nuchal translucency normal results

It is improbable that your infant has Down syndrome or another genetic condition if the ultrasound reveals a normal quantity of fluid in the back of the neck.

With gestational age, nuchal translucency measurement rises. Gestational age is the time between conception and delivery.

The following metrics have a low probability of having genetic disorders:

  • When 11 weeks old, up to 2 mm
  • Up to 2.8 mm at 13 weeks and 6 days.

What do Nuchal translucency abnormal results mean?

There is an increased risk of;

  • Down syndrome
  • Trisomy 18,
  • Trisomy 13,
  • Turner syndrome and,
  • Congenital heart problems,

If there is more fluid than usual in the back of the neck. However, it cannot conclusively determine if the infant has Down syndrome or another genetic condition.

Other tests can be performed if the result is abnormal. Amniocentesis is frequently used as a second test.

How to calculate expected Nuchal translucency?

The following formula is used to evaluate the expected Nuchal translucency. This formula is also used in the Nuchal translucency calculator.

Nuchal translucency= 0.437 + (0.01969 * Crown-rump length).

Crown-rump length and nuchal translucency are both specified in millimeters (mm).

If your child’s NT is a bit higher or lower than the predicted value, that’s okay. All NT readings that are below the 95th percentile are regarded as normal.

Nuchal translucency Risk Table

The likelihood of a genetic condition, severe abnormalities, and death increases with nuchal fold thickness, as shown in the nuchal translucency measurements chart below.

At the 95th percentile, abnormal nuchal translucency first appears; nevertheless, the risk increases noticeably as NT measures increase dramatically.

Nuchal translucencyHealthy babies bornGenetic defectFetal deathMajor fetal abnormalities
3.5-4.4 mm70%21.1%2.7%10%
4.5-5.4 mm50%33.3%3.4%18.5%
5.5-6.4 mm30%50.5%10.1%24.2%
≥6.5 mm15%64.5%19%46.2%


You can use the nuchal translucency calculator to estimate the gestational age of your pregnancy and the probability of genetic abnormalities. Do not become alarmed if your results are irregular.

NT tests are screens, and abnormal results indicate the need for more testing. You still have a chance of giving birth to a healthy child. Discuss with your healthcare practitioner the implications of your test results and their suggested course of action. A genetic counselor can help you weigh your options and review the advantages and disadvantages of additional testing.

If you have any queries regarding the nuchal translucency calculator don’t forget to text us.


What does Nuchal translucency mean?

The test for nuchal translucency determines the nuchal fold thickness. An unborn child’s neck’s back has a particular section of tissue in it. The infant’s risk of Down syndrome and other genetic issues is evaluated by measuring its thickness and help of nuchal translucency calculator.

What does it mean if the NT scan is positive?

If the test is positive, your physician can advise prenatal cell-free DNA screening, another blood test. This test looks at fetal DNA in your bloodstream to determine your baby’s risk for Down syndrome and other chromosome anomalies.

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